Antireflective film, method of producing antireflective film, and eyeglass type display

ABSTRACT

The present invention is an antireflective film, including: a support base, and a pattern composed of a photoresist material formed on the support base, the pattern having a larger size at a point closer to the support base. The present invention provides an antireflective film that is able to give antireflection effect to decrease the reflection of light, a method of producing the same, and an eyeglass type display.

TECHNICAL FIELD

The present invention relates to an antireflective film for collectingvisible light with a shallow incidence angle without reflecting it andfor emitting visible light at a shallow angle without reflecting it, amethod of producing the antireflective film, and an eyeglass typedisplay using the antireflective film.

BACKGROUND ART

The development of devices for virtual reality (VR) has been advancing.Wearing a goggles type VR, it is possible to watch a movie and toconverse with a person remote from each other as if being adjacent to(PATENT LITERATURE 1). It becomes familiar to experience images as if togo beyond space-time, which were shown in SF movies in the past.

In order to obtain real feeling of virtual reality, it has beeninvestigated to reduce the weight and the thickness of the goggles. Itis also necessary to replace the pair of goggles itself to an eyeglasstype (glasses type), which is lighter in weight, and it will becomenecessary to contrive devices that enable to experience VR withouthaving glasses. As a technique to form images in space, holography hasbeen known. This makes it possible to experience VR without havinggoggles or glasses. In the holography, images in space are formed byhighly coherent laser interference. Due to the weight reduction,miniaturization, price reduction, quality improvement, and increasedintensity of laser apparatuses, holography has become familiar recently.It has been proposed a technique to let light through a propagationlayer for light to the vertical direction, which is projected usingholography (PATENT LITERATURE 2). This is constructed such that light ispropagated to the horizontal direction to an eyeglass, and is diffractedto project images to the vertical direction, which is the direction toan eye.

In the holography, resolution and contrast of images are changed due todifferences in accuracy and resolution of a pattern to be diffracted. Atpresent, liquid crystal displays and organic EL displays are much betterin resolution and contrast of images.

If a head mount display is replaced with an eyeglass type display, whichis light in weight, it is possible to reduce the weight substantially.In this case, it becomes necessary to provide a technique to projectoblique incident light that is extremely thin, a thin constitution oflenses to focus on an object at a short distance, and a high qualityantireflective film material to project light with a shallow incidenceangle without reflecting it.

It has long been proposed to provide a display with an antireflectivefilm at the side of eyes (PATENT LITERATURE 3). This allows imagesprojected from a display to be seen in a highly contrast state withoutlosing the intensity. It has also been demonstrated that a multi-layerantireflective film is effective as the antireflective film (PATENTLITERATURE 4). To prevent reflections with respect to visible lightswith various wavelength and lights at various angles, multi-layerantireflective films are favorable.

An antireflective film with a moth eye structure has been proposed(NON-PATENT LITERATURE 1). The reason why moths can detect light withhigh efficiency even in darkness is that the surface of their eye has astructure with repeated minute projections. This structure isartificially formed in an antireflection film, which has been proposed(PATENT LITERATURE 5). In this film, massed pillars with higherrefractive index are formed in which the pillar is finer than thewavelength, finer at the tip and thicker at the substrate side, therebymaking the refractive index be lower at the tip and higher at thesubstrate side. The moth eye structure can realize effect that issimilar in the case of multilayer antireflective film.

The antireflective film with a moth eye structure is formed by imprinttechnique in which a printing block is pushed against resin, and theresin is transformed while heating under certain circumstances. Theimprint method involves a drawback of wearing of the printing block,which makes it impossible to form a pattern. The moth eye structureitself involves a problem that the antireflective function lowers when aforeign matter sticks to the pillars or the pillar breaks.

CITATION LIST Patent Literature

-   PATENT LITERATURE 1: Japanese Patent Laid-Open Publication (Kokai)    No. H06-236432-   PATENT LITERATURE 2: US 2013/0021392A1-   PATENT LITERATURE 3: Japanese Patent Laid-Open Publication (Kokai)    No. H05-215908-   PATENT LITERATURE 4: Japanese Patent Laid-Open Publication (Kokai)    No. H05-264802-   PATENT LITERATURE 5: Japanese Patent Laid-Open Publication (Kokai)    No. 2004-77632

Non Patent Literature

-   NON-PATENT LITERATURE 1: Optica Acta: International Journal of    Optics, Vol. 29, p993-1009 (1982)

SUMMARY OF INVENTION Technical Problem

The present invention was accomplished in view of the above-describedproblems. It is an object of the present invention to provide anantireflective film that is able to give antireflection effect todecrease the reflection of light, a method of producing the same, and aneyeglass type display.

Solution to Problem

To solve the above problems, the present invention provides anantireflective film, comprising:

a support base, and

a pattern composed of a photoresist material formed on the support base,the pattern having a larger size at a point closer to the support base.

The inventive antireflective film is able to give antireflection effectto decrease the reflection of light.

It is preferable that the pattern have a pitch of 400 nm or less.

The antireflective film having such a pattern pitch is able to preventdiffuse reflection on the pattern.

It is preferable that the photoresist material contain a polymercompound having an aromatic group.

With the photoresist material like this, the antireflective film becomeseasy in manufacturing.

The photoresist material preferably contains a polymer compound thatcontains 85% or more of a repeating unit having at least one structureselected from the group consisting of naphthalene, fluorene, anthracene,and cyclopentadienyl complexes.

The photoresist material preferably contains a polymer compound thatcontains 50% or more of a repeating unit having any of styrenesubstituted with iodine or bromine, benzene (meth)acrylate substitutedwith iodine or bromine, and benzene (meth)acrylamide substituted withiodine or bromine.

The photoresist material preferably has a refractive index of 1.6 ormore with respect to visible light having a wavelength of 590 to 610 nm.

With the photoresist material described above, it becomes easy toproduce a moth eye pattern to achieve still more enhanced antireflectioneffect.

It is preferable that the pattern be covered with a low-refractive-indexmaterial having a refractive index of 1.45 or less with respect tovisible light having a wavelength of 590 to 610 nm.

In the antireflective film like this, it is possible to prevent loweringof antireflection effect due to pattern collapse.

The antireflective film is preferably such that the transmittance ofvisible light having a wavelength of 400 to 800 nm is 80% or more.

The antireflective film with such transmittance can be preferably usedfor a light-weight and thin eyeglass-type head mount display by whichlight with higher brightness and higher contrast can be seen.

The present invention also provides an eyeglass type display,comprising:

a self-emitting display selected from the group consisting of liquidcrystal, organic EL, and micro LED installed on a substrate at the sideof an eyeball of the eyeglass type display, and

a convex lens for focusing installed on the side of an eyeball of theself-emitting display,

wherein the antireflective film described above is formed on a surfaceof the convex lens.

The inventive eyeglass type display can be preferably used as alight-weight and thin eyeglass-type head mount display by which lightwith higher brightness and higher contrast can be seen.

The present invention also provides a method of producing anantireflective film, comprising:

coating a support base with a photoresist material, and

exposing and developing the photoresist material to form a patternhaving a larger size at a point closer to the support base.

The inventive method of producing an antireflective film facilitatesmanufacturing an antireflective film that is allowed to haveantireflective effect to exhibit lower reflection of light.

The method of producing an antireflective film preferably comprises

forming an organic film as the support base on a substrate using anorganic film-forming composition,

wherein the pattern is formed on the organic film using the photoresistmaterial.

By the production method like this, the inventive antireflective filmcan be manufactured more easily.

It is preferable to set the pattern to have a pitch of 400 nm or less.

With the pattern pitch like this, it is possible to manufacture anantireflective film capable of preventing diffuse reflection on thepattern.

It is preferable to use the photoresist material containing a polymercompound having an aromatic group.

Using the photoresist material like this, the antireflective film of thepresent invention can be manufactured more easily.

It is preferable to use the photoresist material containing a polymercompound that contains 85% or more of a repeating unit having at leastone structure selected from the group consisting of naphthalene,fluorene, anthracene, and cyclopentadienyl complexes.

It is preferable to use the photoresist material containing a polymercompound that contains 50% or more of a repeating unit having any ofstyrene substituted with iodine or bromine, benzene (meth)acrylatesubstituted with iodine or bromine, and benzene (meth)acrylamidesubstituted with iodine or bromine.

It is preferable to use the photoresist material having a refractiveindex of 1.6 or more with respect to visible light having a wavelengthof 590 to 610 nm.

Using the photoresist material described above, it is possible tomanufacture an antireflective film in which a moth eye pattern is easilyformed, and still more enhanced antireflection effect can be achieved.

It is preferable to cover the formed pattern with a low-refractive-indexmaterial having a refractive index of 1.45 or less with respect tovisible light having a wavelength of 590 to 610 nm.

Including the step like this, the production method makes it possible tomanufacture an antireflective film that is prevented from lowering ofantireflection effect due to pattern collapse.

Advantageous Effects of Invention

As described above, in the antireflective film of the present invention,a moth eye-type antireflective film is successfully formed with apattern in a tapered profile formed by exposure and development using aphotoresist based on a highly refractive polymer. This makes it possibleto obtain antireflective effect, which exhibits lower reflection ofvisible light even to incident light and emitted light with a shallowangle. Accordingly, when it is combined with a lens(es) with a highrefractive index, light emitted from liquid crystal, organic EL, andmicro LED that are installed near eyes can be seen in the state ofhigher contrast and higher brightness. The inventive method of producingan antireflective film makes it possible to form the inventiveantireflective film easily. Moreover, using the inventive antireflectivefilm, it is possible to realize an eyeglass type display which issubstantially light in weight and thin compared to previous head mountdisplays.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic sectional view showing an example of the inventiveantireflective film after forming a highly refractive resist pattern;

FIG. 2 is a schematic sectional view showing an example of the inventiveantireflective film after forming a highly refractive resist pattern andforming a lower refractive film thereon;

FIG. 3 is a schematic top view showing an example of a pattern layout ofthe inventive antireflective film after forming a highly refractiveresist pattern;

FIG. 4 is a schematic top view showing another example of a patternlayout of the inventive antireflective film after forming a highlyrefractive resist pattern;

FIG. 5 is a schematic sectional view showing an example of the case ofwearing the inventive eyeglass type display;

FIG. 6 is a schematic sectional view showing a method of measuring lighttransmittance of the inventive antireflective film in Examples.

DESCRIPTION OF EMBODIMENTS

As described above, it has been known that excellent antireflectiveeffect can be obtained by installing a film with a lower refractiveindex at the side of air (eyes), a film with a higher refractive indexat the side of generating light, which is opposite to the eye, and amultilayer film therebetween in which the refractive index altersgradually. However, the refractive index is an intrinsic value of eachmaterial. Accordingly, to change the refractive index gradually, it isnecessary to laminate films of materials with the refractive indexesbeing different from each other, and it has been difficult to adjust therefractive index. It is also conceivable to alter the refractive indexof the film to be laminated by blending a material with a higherrefractive index and a material with a lower refractive index, togetherwith altering the ratio of blending. However, the material with a higherrefractive index and the material with a lower refractive index arelargely different in polarity in many cases, and are not mixed afterblending thereby. Accordingly, this method is not popular either. Hence,it is also conceivable to use a film in which the moth eye patterndescribed above is formed as an antireflective film. In general, themoth eye pattern is formed by imprint technique to process a resin filmby pressing a mold called stamper while heating the resin film.

The present inventors diligently investigated to achieve the foregoingobjects and consequently found that the moth eye pattern is successfullyimproved greatly in the throughput if it can be formed by exposure anddevelopment, and still more enhanced antireflection effect can beobtained using a highly refractive material as a photoresist to form themoth eye pattern; thereby bringing the present invention to completion.

That is, the present invention is an antireflective film, comprising:

a support base, and

a pattern composed of a photoresist material formed on the support base,the pattern having a larger size at a point closer to the support base.

Hereinafter, the present invention will be specifically described byreferring to FIGS., but the present invention is not limited thereto.

<Antireflective Film>

The present invention provides an antireflective film in which a patterncomposed of a photoresist material is formed on a support base, and thepattern has a larger size at a point closer to the support base, thatis, the pattern is flared toward the support base.

An example of the inventive antireflective film is shown in FIG. 1 as aschematic sectional view. The antireflective film 101 of FIG. 1 is afilm in which a pattern 13 (moth eye pattern) composed of a photoresistmaterial 12 is formed on a support base 11, with the pattern 13 having alarger size at a point closer to the support base 11.

The moth eye pattern may have any layout, when it is observed from theabove, such as a crosswise arrangement as shown in FIG. 3, anarrangement shown in FIG. 4, and other arrangement, but the pattern ispreferably in the same pitch and the same size. With the pattern in thesame size and pitch, the refractive index of the film becomes uniformand is favorable.

In the antireflective film of the present invention, the transmittanceof visible light having a wavelength of 400 to 800 nm is preferably 80%or more.

[Pattern having a larger size at a point closer to Support Base (MothEye Pattern)]

The moth eye pattern 13 is preferably set to have a pitch smaller thanthe wavelength of the visible light. This successfully prevents diffusereflection on the moth eye pattern 13. Since the shortest wavelength inthe visible light is about 400 nm, the pitch of the pattern ispreferably 400 nm or less, more preferably 300 nm or less.

The height of the moth eye pattern 13 is preferably 50 nm or more and1000 nm or less, more preferably 100 nm or more and 800 nm or less.

The resin film formed by common imprint method has a refractive index ofabout 1.5, but a moth eye pattern having a higher refractive index than1.5 can be formed from a photoresist material as in the presentinvention. With higher refractive index, it is possible to achievehigher antireflection effect to emit or introduce shallower light.Accordingly, the photoresist material preferably has a refractive indexof 1.6 or more, more preferably 1.65 or more, still more preferably 1.7or more with respect to visible light having a wavelength of 590 to 610nm.

The moth eye pattern 13 have to be formed such that the upper part has asmaller size, and the face adjoined to the underneath support base has alarger size as shown in FIG. 1. Although the profile of the moth eyepattern 13 shown in FIG. 1 has a triangular shape, it may be a trapezoidshape, in which the upper part is planer, or a shape of halved oval. Inany shape, this makes the refractive index at the upper part lower andthe refractive index at the lower part higher. The methods to form apattern with a tapered shape like this include a method using a resistmaterial with higher absorption and a method using a resist materialwith a lower dissolution contrast. For example, the resist materialhaving a naphthalene-containing structure has appropriate absorption ofKrF excimer laser at a wavelength of 248 nm and ArF excimer laser at awavelength of 193 nm, thereby being preferable since a moth eye patterncan be formed by lithography using these excimer laser.

The photoresist material preferably has an aromatic group, and a polymercompound having a condensed aromatic ring is more preferable due to thehigher refractive index. For example, as the resist material having acondensed aromatic ring with higher refractive index, a resist materialhaving an acid-labile group of condensed aromatic ring is exemplified inJP 2010-237662A, JP 2010-237661A, JP 2011-150103A, JP 2011-138107A, andJP 2011-141471A. The preferable examples thereof also include a resistmaterial that contains any of acenaphthylene described in JP2002-119659A, vinylferrocene described in JP 2014-119659A,hydroxyvinylnaphthalene described in JP 2002-107933A, andhydroxynaphthalene methacrylate described in JP 2007-114728A since theyhave a higher refractive index. The resist material described in JPH05-204157A, which contains hydroxystyrene substituted with bromine oriodine, has higher refractive index and is preferable thereby.

The following are exemplified as a monomer that contains an acid-labilegroup of condensed aromatic ring.

The following are exemplified as a monomer to obtain a repeating unithaving a naphthalene structure.

The following are exemplified as a monomer to obtain a repeating unithaving any of styrene substituted with iodine or bromine, benzene(meth)acrylate substituted with iodine or bromine, and benzene(meth)acrylamide substituted with iodine or bromine.

The following are exemplified as a monomer to obtain a repeating unithaving an anthracene structure.

The following are exemplified as a monomer to obtain a repeating unithaving a cyclopentadienyl complex. The following cyclopentadienylcomplexes are preferably ferrocene.

In the formulae, R represents a hydrogen atom or a methyl group, and Mrepresent any of Fe, Co, Ni, Cr, and Ru.

The aforementioned polymer compounds are suitable, particularly for abase resin of a positive type resist material with higher refractiveindex. In a positive type resist material composed of the polymercompound like this as a base material, together with organic solvent,acid generator, a basic compound, and surfactant formulated theretobeing appropriately combined in accordance with needs, the polymercompound dissolves into developer at an accelerated rate in the exposedpart due to catalytic reaction, thereby allowing the positive typeresist material to have extremely high sensitivity, to form a resistfilm with high dissolution contrast and resolution, to have exposuremargin and an excellent process adaptability, and to form a moth eyepattern with higher refractive index with respect to visible light afterexposure.

The photoresist material preferably contains a polymer compound, amongthe polymer compounds described above, which contains 85% or more of arepeating unit having at least one structure selected from the groupconsisting of naphthalene, fluorene, anthracene, and cyclopentadienylcomplexes.

The photoresist material preferably contains a polymer compound thatcontains 50% or more of a repeating unit having any of styrenesubstituted with iodine or bromine, benzene (meth)acrylate substitutedwith iodine or bromine, and benzene (meth)acrylamide substituted withiodine or bromine.

Additionally, the resist material is allowed to decrease diffusion rateof acid in the resist film to further improve the resolution by adding abasic compound, and the application property of the resist material ismore improved or controllable by adding surfactant.

The resist material may contain an acid generator to activate thechemically amplified positive type resist material used for thepatterning process of the production method that will be describedlater, for example, a compound capable of generating an acid byresponding to an active beam or a radiation beam (photo acid generator)may be contained therein. As to the photo acid generator component, anycompound capable of generating an acid by exposure to a high energy beamcan be used. Examples of the suitable photo acid generator include asulfonium salt, an iodonium salt, a sulfonyldiazomethane, anN-sulfonyloxyimide, and an oxime-O-sulfonate type acid generator.

Illustrative examples of the acid-generator are described in paragraphs[0122] to [0142] of JP 2008-111103A, for example. These compounds may beused solely or as a mixture of two or more.

Illustrative examples of the components that can be formulated to theresist material include organic solvent, a basic compound (quencher),and surfactant described in paragraphs [0144] to [0145], paragraphs[0146] to [0164], and paragraphs [0165] to [0166] of JP 2008-111103Arespectively, together with dissolution inhibitor described inparagraphs [0155] to [0178] of JP 2008-122932A. It is also possible toadd a polymer type quencher described in JP 2008-239918A. In accordancewith needs, acetylene alcohols can be added as an optional component,and illustrative examples thereof include acetylene alcohols describedin paragraphs [0179] to [0182] of JP 2008-122932A.

These components orient on the resist surface after coating thereof toimprove the profile accuracy after the patterning. The polymer-typequencher also has the effects to prevent film loss of the pattern when atop coat for immersion exposure is formed thereon as well as rounding ofthe pattern head.

When the acid generator is formulated, the formulate amount ispreferably 0.1 to 50 parts by mass based on 100 parts by mass of thebase resin. When the basic compound (quencher) is formulated, theformulate amount is preferably 0.01 to 20 parts by mass, particularly0.02 to 15 parts by mass based on 100 parts by mass of the base resin.When the dissolution inhibitor is formulated, the formulate amount ispreferably 0.5 to 50 parts by mass, particularly 1.0 to 30 parts by massbased on 100 parts by mass of the base resin. When the surfactant isformulated, the formulate amount is preferably 0.0001 to 10 parts bymass, particularly 0.001 to 5 parts by mass based on 100 parts by massof the base resin.

The formulate amount of organic solvent is preferably 100 to 10,000parts by mass, particularly 200 to 8,000 parts by mass based on 100parts by mass of the base resin.

[Support Base]

The support base can be any material as far as it can support the motheye pattern, such as an underlayer film and a substrate without beingparticularly limited thereto. The underlayer film may be any of anorganic film and an inorganic film. It is also possible to form a motheye pattern directly on a substrate without providing an underlayerfilm. However, the underlayer film and the substrate are preferable tobe highly transparent with respect to visible light. Additionally, it isalso preferable that the substrate and the underlayer film each havehigher refractive index. When a substrate is used as the support base,it is preferable to use a substrate treated with HMDS(Hexamethyldisilazan).

[Low-Refractive-Index Material]

FIG. 2 is a schematic sectional view showing an example of the inventiveantireflective film in which the moth eye patterns 13 are coated withthe low-refractive-index material 14. As shown in FIG. 2, the gapsbetween the moth eye patterns 13, which are formed by exposing anddeveloping photoresist, may be buried by the low-refractive-indexmaterial 14 to form an antireflective film 111. Since collapsing of themoth eye patterns 13 causes lowering of the antireflection effect, theburying of the moth eye patterns 13 is also effective to prevent themoth eye patterns 13 from collapsing when it is touched.

As the low-refractive-index material for burring the moth eye pattern, amaterial that is applicable by spin-coating is preferable, and fluorinepolymers can be exemplified, for example. Additionally, thelow-refractive-index material preferably has a refractive index of 1.45or less. Teflon (trade mark) type polymer has a refractive index of 1.35in the area of visible light. Even in methacrylate having a pendantfluoroalkyl group, the refractive index is about 1.42. For example, JP2008-257188A shows a crosslinkable underlayer film with a lowerrefractive index having a fluoroalcohol group. As a material with astill lower refractive index, porous silica films can be exemplified.The refractive index is decreased by enlarging the size of the pores orincreasing the ratio of the pores, and can be decreased to about 1.25thereby.

The low-refractive-index material for burring the moth eye pattern ispreferably dissolved into a solvent that does not dissolve a resistpattern and applied onto a moth eye pattern by spin-coating.Illustrative examples of the solvent that does not dissolve a resistpattern include alcohol type solvents, ether type solvents, hydrocarbontype solvents, and fluorine type solvents.

The inventive antireflective film, in which a moth eye structure isformed, allows the image projected from a display of liquid crystal,organic EL, or micro LED to emit obliquely with high brightness and highcontrast. It is also possible to prevent reflection of oblique incidentlight from the opposite side of a display not only reflection in whichlight emitted from the display side returns to the display side.

<Eyeglass Type Display>

The present invention also provides an eyeglass type display,comprising:

a self-emitting display selected from the group consisting of liquidcrystal, organic EL, and micro LED installed on a substrate at the sideof an eyeball of the eyeglass type display, and

a convex lens for focusing installed on the side of an eyeball of theself-emitting display,

wherein the inventive antireflective film is formed on a surface of theconvex lens.

FIG. 5 is a schematic sectional view showing an example of the case ofwearing the inventive eyeglass type display. The self-emitting display 2is provided at the side of an eyeball of the eyeglass substrate 1. Theself-emitting display 2 is made of any of liquid crystal, organic EL, ormicro LED. The convex lens 3 is provided on the side of an eyeball ofthe self-emitting display 2. Each convex lens 3 is provided for focusinglight emitted from the self-emitting display 2 on the eye 5. Theinventive antireflective film 101 is provided at the side of an eyeballof the convex lens 3. The antireflective film 101 is as described above.It is also possible to use the antireflective film 111 instead of theantireflective film 101.

The inventive eyeglass type display makes it possible to realize aneyeglass type display, which is substantially light in weight and thincompared to previous head mount displays.

<Method of Producing Antireflective Film>

The present invention also provides a method of producing anantireflective film, comprising:

coating a support base with a photoresist material, and

exposing and developing the photoresist material to form a patternhaving a larger size at a point closer to the support base.

As a support base and a photoresist material used in this process, it ispossible to use ones described in the explanation of the inventiveantireflective film.

The inventive method of producing an antireflective film preferablyincludes a step of applying the resist material described above onto asupport base, a step of heat treatment followed by exposure to highenergy beam, and a step of development using developer.

In the step of exposure to high energy beam, it is possible to use alight source such as ArF excimer laser at a wavelength of 193 nm, KrFexcimer laser at a wavelength of 248 nm, i-beam at a wavelength of 365nm, and accelerated electron beam.

For example, the resist material described above is applied onto asubstrate for manufacturing an integrated circuit or a layer to beprocessed on the substrate (Si, SiO₂, SiN, SiON, TiN, WSi, BPSG, SOG, anorganic antireflective film; a flexible substrate such as thin filmglass, PEN, PET, or polyimide; or a device on which an organic EL,liquid crystal, or micro LED have been formed) by appropriate coatingmethod such as spin-coating, roll coating, flow-coating, dip coating,spray coating, and doctor coating to have a thickness of coating film of0.1 to 2.0 μm. This is pre baked on a hot plate at 60 to 150° C. for 10seconds to 30 minutes, preferably at 80 to 120° C. for 30 seconds to 20minutes.

Then, this is exposed to a high energy beam using a light sourceselected from ultraviolet beam, a far ultraviolet beam, an electronbeam, an X-ray, a soft X-ray, an excimer laser, a γ-ray, a synchrotronradiation ray, and EUV to form an intended pattern through a certainmask or directly. The exposure is preferably performed to have anexposure dose of about 1 to 200 mJ/cm², particularly 10 to 100 mJ/cm²,or about 0.1 to 100 μC/cm², particularly 0.5 to 50 μC/cm². Subsequently,this is subjected to PEB on a hot plate, preferably at 60 to 150° C. for10 seconds to 30 minutes, more preferably at 80 to 120° C. for 30seconds to 20 minutes.

Additionally, this is developed by ordinary method such as a dip method,a puddle method, and a spray method preferably using a developer ofaqueous alkaline solution such as 0.1 to 5 mass %, more preferably 2 to3 mass % of tetramethylammonium hydroxide (TMAH), choline hydroxide,tetraethylammonium hydroxide (TEAH), tetrapropylammonium hydroxide(TPAH), tetrabutylammonium hydroxide (TBAH), benzyltrimethylammoniumhydroxide, and benzyltriethylammonium hydroxide, preferably 3 seconds to3 minutes, more preferably 5 seconds to 2 minutes. Through thisdevelopment, the part irradiated with light is dissolved into thedeveloper, and the part that have not been exposed is not dissolved,thereby forming the intended positive type pattern on the substrate.

As the mask pattern used for exposure to form a moth eye pattern, it ispossible to use the one shown in JP 2010-186064A, for example. That is,it is possible use a line-and-space pattern arranged in the Y directionand the X direction, a latticed pattern, and a dot pattern. As for theillumination, illustrative examples thereof include a method ofperforming dipole illumination in the X direction and the Y directiontwice, and a method of performing one exposure with a cross poleillumination or annular illumination.

The inventive method of producing an antireflective film like this makesit possible to easily manufacture an antireflective film that exhibitsantireflection effect with lower reflection of visible light even toincident light and emitted light with a shallow angle.

EXAMPLE

Hereinafter, the present invention will be explained specifically byshowing Examples and Comparative Examples, but the present invention isnot limited thereto.

As the high refractive index material for forming a moth eye pattern,High refractive index resist polymers-1 to 8 and Underlayer film resistpolymer-1 for forming an underlayer film as a support base obtained byradical polymerization as described below were prepared.

High refractive index resist polymer-1

weight average molecular weight (Mw)=6,800

molecular weight distribution (Mw/Mn)=1.91

High refractive index resist polymer-2

weight average molecular weight (Mw)=7,100

molecular weight distribution (Mw/Mn)=1.61

High refractive index resist polymer-3

weight average molecular weight (Mw)=7,900

molecular weight distribution (Mw/Mn)=1.67

High refractive index resist polymer-4

weight average molecular weight (Mw)=8,800

molecular weight distribution (Mw/Mn)=1.77

High refractive index resist polymer-5

weight average molecular weight (Mw)=8,800

molecular weight distribution (Mw/Mn)=1.77

High refractive index resist polymer-6

weight average molecular weight (Mw)=8,800

molecular weight distribution (Mw/Mn)=1.77

High refractive index resist polymer-7

weight average molecular weight (Mw)=7,600

molecular weight distribution (Mw/Mn)=1.63

High refractive index resist polymer-8

weight average molecular weight (Mw)=8,800

molecular weight distribution (Mw/Mn)=1.77

Underlayer film resist polymer-1

weight average molecular weight (Mw)=8,400

molecular weight distribution (Mw/Mn)=1.98

Photo-acid generators: PAG1, PAG2, PAG3 (see the following structuralformulae)

Basic compounds: Quenchers 1 and 2 (see the following structuralformulae)

Acid generator: AG1 (see the following structural formula)

Crosslinking agent: CR1 (see the following structural formula)

Organic Solvents:

propylene glycol monomethyl ether acetate (PGMEA) cyclohexanone (CyH)

High refractive index resist polymer, Photo-acid generator, Basiccompound, and solvent containing 100 ppm of FC-4430, which is asurfactant manufactured by 3M, were blended in the composition of Table1, spin coated onto a silicon wafer, and baked at 110° C. for 60 secondsto form a photoresist film with the film thickness of 250 nm. Therefractive index of this film was measured by spectroscopicellipsometry. The results are shown in Table 1.

TABLE 1 Refractive index High refractive at wavelength index resistpolymer Acid generator Basic compound Solvent of 600 nm Resist (parts bymass) (parts by mass) (parts by mass) (part by mass) n value k valueResist-1 High refractive PAG 1 Quencher 1 PGMEA 1.67 0.0 index resist(1.8) (0.5) (100) polymer-1 (15.0) Resist-2 High refractive PAG 1Quencher 1 PGMEA 1.68 0.0 index resist (1.8) (0.5) (100) polymer-2(15.0) Resist-3 High refractive PAG 1 Quencher 1 PGMEA 1.68 0.0 indexresist (1.8) (0.5) (100) polymer-3 (15.0) Resist-4 High refractive PAG 1Quencher 1 PGMEA 1.63 0.0 index resist (1.8) (0.5) (100) polymer-4(15.0) Resist-5 High refractive PAG 1 Quencher 1 PGMEA 1.64 0.0 indexresist (1.8) (0.5) (100) polymer-5 (15.0) Resist-6 High refractive PAG 1Quencher 1 PGMEA 1.70 0.0 index resist (1.8) (0.5) (70) polymer-6 (15.0)CyH (30) Resist-7 High refractive PAG 2 Quencher 1 PGMEA 1.64 0.0 indexresist (1.5) (0.5) (100) polymer-7 (15.0) Resist-8 High refractive PAG 3Quencher 2 PGMEA 1.68 0.0 index resist (2.0) (0.8) (100) polymer-1(15.0) Resist-9 High refractive PAG 2 Quencher 1 PGMEA 1.62 0.0 indexresist (1.5) (0.5) (100) polymer-8 (15.0)

Under layer film resist polymer, Crosslinking agent, thermal-acidgenerator, and solvent containing 100 ppm of FC-4430, which is asurfactant manufactured by 3M, were blended in the composition of Table2, spin coated onto a silicon wafer, and crosslinked by baking at 200°C. for 60 seconds to form an underlayer film with the film thickness of200 nm. The refractive index of this film was measured by spectroscopicellipsometry. The results are shown in Table 2.

TABLE 2 Refractive index Crosslinking Acid at wavelength UnderlayerPolymer agent generator Solvent of 600 nm film (parts by mass) (parts bymass) (parts by mass) (parts by mass) n value k value UDL-1 Underlayerfilm CR 1 AG 1 PGMEA 1.69 0.0 resist polymer-1 (2.0) (0.5) (100) (15.0)CyH (100)

Teflon (registered trade mark) AF polymer manufactured by Du Pont-MitsuiFluorochemicals Co., Ltd. and solvent were blended in the composition ofTable 3, spin coated onto a silicon wafer, and crosslinked by baking at100° C. for 60 seconds to form a low refractive index-over coat filmwith the film thickness of 250 nm. The refractive index of this film wasmeasured by spectroscopic ellipsometry. The results are shown in Table3.

TABLE 3 Top Refractive index at coat Polymer Solvent wavelength of 600nm film (parts by mass) (parts by mass) n value k value TCL-1 TeflonAF1600 Perfluorotributylamine 1.35 0.0 (10.0) (200)

Onto a synthesis quartz substrate, an underlayer film solution wasapplied to form UDL-1 film with the film thickness of 200 nm by the samespin coat method and baking conditions as described above. The solutionof photoresist was applied thereonto under the same conditions and bakedat 110° C. for 60 seconds to form a photoresist film with the filmthickness of 250 nm. This was exposed using KrF excimer laser scannerS-206D manufactured by Nikon Corporation (NA: 0.82, dipole illumination)and 6% half-tone phase shift mask to form a pattern in the X directionof 130 nm line-and-space and a pattern in the Y direction of 130 nmline-and-space at the same position so as to intersect with the patternin the X direction. After the exposure, this was baked at a temperaturedescribed in Table 4 for 60 seconds (PEB) and developed with 2.38 mass %aqueous tetramethylammonium hydroxide (TMAH) solution for 60 seconds toform a pillar pattern on the intersecting part of the line-and-spacepattern.

The cross section of the developed pattern was observed and photographedto observe that a pillar pattern with the pitch of 260 nm was formed ina tapered profile with the side wall angle of 70 to 80°.

In Comparative Examples 2 and 3, the resist films were not subjected topatterning exposure.

In Example 10, a low refractive index-over coat film was formed underthe same conditions as described above after a pattern was formed tobury the gaps between the patterns by TCL-1 as in FIG. 2. In ComparativeExample 3, a TCL-1 film was formed on the photoresist film under thesame conditions.

As shown in FIG. 6, on the antireflective film 101, the illuminationintensity at the angle of 60° thereof was measured by the method inwhich a slit with the width of 1 mm was formed in the shielding film 103on the back side of the synthesis quartz substrate on which theantireflective film 101 was not formed, and this slit was used as apoint light source, which was illuminated with the LED illumination 104of 1200 lumen white light in a fluorescent type attached thereto. InComparative Examples 1 to 3, the same measurement was conducted. Theresults are shown in Table 4.

TABLE 4 Underlayer Resist Over coat Exposure dose PEB temperatureCandela film film film (mJ/cm²) (° C.) (cd/m²) Example 1 UDL-1 Resist-1— 41 120 14 Example 2 UDL-1 Resist-2 — 24 110 16 Example 3 UDL-1Resist-3 — 28 110 15 Example 4 UDL-1 Resist-4 — 39 120 15 Example 5UDL-1 Resist-5 — 22 100 14 Example 6 UDL-1 Resist-6 — 23 100 14 Example7 UDL-1 Resist-7 — 21 90 16 Example 8 UDL-1 Resist-8 — 65 110 17 Example9 — Resist-1 — 32 110 12 Example 10 UDL-1 Resist-1 TCL-1 41 110 11Example 11 UDL-1 Resist-9 — 43 120 16 Comparative — — — — — 4 Example 1Comparative UDL-1 Resist-1 — — — 6 Example 2 Comparative UDL-1 Resist-1TCL-1 — — 7 Example 3

As shown in Table 4, each inventive antireflective film produced inExamples 1 to 11 showed higher illumination of the transmitted light. Onthe other hand, Comparative Examples 1 to 3 showed lower illumination ofthe transmitted light than that of the inventive antireflective film.

From the foregoing, it was revealed that the inventive antireflectivefilm successfully gave antireflection effect to bring lower reflectionof light.

It is to be noted that the present invention is not restricted to theforegoing embodiment. The embodiment is just an exemplification, and anyexamples that have substantially the same feature and demonstrate thesame functions and effects as those in the technical concept describedin claims of the present invention are included in the technical scopeof the present invention.

1. An antireflective film, comprising: a support base, and a patterncomposed of a photoresist material formed on the support base, thepattern having a larger size at a point closer to the support base. 2.The antireflective film according to claim 1, wherein the pattern has apitch of 400 nm or less.
 3. The antireflective film according to claim1, wherein the photoresist material contains a polymer compound havingan aromatic group.
 4. The antireflective film according to claim 2,wherein the photoresist material contains a polymer compound having anaromatic group.
 5. The antireflective film according to claim 1, whereinthe photoresist material contains a polymer compound that contains 85%or more of a repeating unit having at least one structure selected fromthe group consisting of naphthalene, fluorene, anthracene, andcyclopentadienyl complexes.
 6. The antireflective film according toclaim 2, wherein the photoresist material contains a polymer compoundthat contains 85% or more of a repeating unit having at least onestructure selected from the group consisting of naphthalene, fluorene,anthracene, and cyclopentadienyl complexes.
 7. The antireflective filmaccording to claim 1, wherein the photoresist material contains apolymer compound that contains 50% or more of a repeating unit havingany of styrene substituted with iodine or bromine, benzene(meth)acrylate substituted with iodine or bromine, and benzene(meth)acrylamide substituted with iodine or bromine.
 8. Theantireflective film according to claim 2, wherein the photoresistmaterial contains a polymer compound that contains 50% or more of arepeating unit having any of styrene substituted with iodine or bromine,benzene (meth)acrylate substituted with iodine or bromine, and benzene(meth)acrylamide substituted with iodine or bromine.
 9. Theantireflective film according to claim 1, wherein the photoresistmaterial has a refractive index of 1.6 or more with respect to visiblelight having a wavelength of 590 to 610 nm.
 10. The antireflective filmaccording to claim 1, wherein the pattern is covered with alow-refractive-index material having a refractive index of 1.45 or lesswith respect to visible light having a wavelength of 590 to 610 nm. 11.The antireflective film according to claim 1, wherein the transmittanceof visible light having a wavelength of 400 to 800 nm is 80% or more.12. An eyeglass type display, comprising: a self-emitting displayselected from the group consisting of liquid crystal, organic EL, andmicro LED installed on a substrate at the side of an eyeball of theeyeglass type display, and a convex lens for focusing installed on theside of an eyeball of the self-emitting display, wherein theantireflective film according to claim 1 is formed on a surface of theconvex lens.
 13. A method of producing an antireflective film,comprising: coating a support base with a photoresist material, andexposing and developing the photoresist material to form a patternhaving a larger size at a point closer to the support base.
 14. Themethod of producing an antireflective film according to claim 13,further comprising: forming an organic film as the support base on asubstrate using an organic film-forming composition, wherein the patternis formed on the organic film using the photoresist material.
 15. Themethod of producing an antireflective film according to claim 13,wherein the pattern has a pitch of 400 nm or less.
 16. The method ofproducing an antireflective film according to claim 13, wherein thephotoresist material contains a polymer compound having an aromaticgroup.
 17. The method of producing an antireflective film according toclaim 13, wherein the photoresist material contains a polymer compoundthat contains 85% or more of a repeating unit having at least onestructure selected from the group consisting of naphthalene, fluorene,anthracene, and cyclopentadienyl complexes.
 18. The method of producingan antireflective film according to claim 13, wherein the photoresistmaterial contains a polymer compound that contains 50% or more of arepeating unit having any of styrene substituted with iodine or bromine,benzene (meth)acrylate substituted with iodine or bromine, and benzene(meth)acrylamide substituted with iodine or bromine.
 19. The method ofproducing an antireflective film according to claim 13, wherein thephotoresist material has a refractive index of 1.6 or more with respectto visible light having a wavelength of 590 to 610 nm.
 20. The method ofproducing an antireflective film according to claim 13, furthercomprising covering the formed pattern with a low-refractive-indexmaterial having a refractive index of 1.45 or less with respect tovisible light having a wavelength of 590 to 610 nm.